Field of the Invention
The invention relates to a configuration for controlling an occupant restraint device in a motor vehicle. The configuration contains two acceleration sensors with differently oriented sensitivity axes and an evaluator for evaluating sensor signals. The evaluator outputs first and second enable signals in dependence on the output signals from the acceleration sensors and the occupant restraint device is triggered in dependence on the enable signals.
A known configuration includes an acceleration sensor for detecting a collision. If an evaluator ascertains from the acceleration signal of the acceleration sensor that a sufficiently strong impact is occurring, then the associated occupant restraint device, such as an air bag, belt tightener, or the like is tripped. According to Published, Non-Prosecuted German Patent Application DE 40 16 644 A1, such a configuration contains a mechanical acceleration switch, whose sensitivity axis is oriented the same way as that of the acceleration sensor. The acceleration switch in particular prevents mistaken tripping because of a defective acceleration sensor or evaluator. Published, Non-Prosecuted German Patent Application DE 40 16 644 A1 also proposes replacing the acceleration switch with a further acceleration sensor and an evaluation circuit downstream from it.
From International Patent Application WO 89/11986, a configuration for controlling an occupant restraint device of a motor vehicle is known that has two acceleration sensors, with differently oriented sensitivity axes. The first acceleration sensor is sensitive to accelerations parallel to the longitudinal axis of the vehicle, and the second acceleration sensor is sensitive to transverse vehicle accelerations. An evaluator evaluates the acceleration signals furnished by the acceleration sensors and activates the associated occupant restraint device when the longitudinal vehicle acceleration exceeds a threshold value, which is set high, or when the amount and direction of an acceleration vector, formed from the longitudinal and transverse acceleration signals, exceeds predetermined values. Thus the occupant restraint device is also tripped in an oblique collision which is highly dangerous for the occupants, but in which the longitudinal acceleration alone would not exceed its assigned threshold value.
From Published, Non-Prosecuted German Patent Application DE 37 17 427 A1, a device for tripping an occupant restraint device is known which is meant to be tripped in the event of a frontal collision or an oblique collision from the front, but not in a side or rear-end collision. To that end, the configuration includes two sensors disposed at an angle of less than 90.degree. from one another, each of them being oriented approximately .+-.30.degree. from the longitudinal axis of the vehicle. The restraint is tripped when both sensors furnish a significant signal.
From Published, Non-Prosecuted German Patent Application DE 195 37 546 A1, a device for tripping an occupant restraint device with two sensors disposed orthogonally to one another is known, in which to reduce the computing power of an evaluator that processes the signals, only the signal of a sensor from whose direction a collision is expected is evaluated.